Mode of delivery and problems in subsequent births: A register-based study from Finland

La Trobe University, Melbourne, Victoria, Australia
American Journal of Obstetrics and Gynecology (Impact Factor: 4.7). 08/2005; 193(1):169-77. DOI: 10.1016/j.ajog.2004.11.007
Source: PubMed


The purpose of this study was to investigate the effects of delivery on problems in subsequent births.
This was a cohort study that used register data for 73,104 mothers who had their first birth from 1987 to 1989 and subsequent births from 1987 to1998. Three analyses were performed: (1) examination of second births by mode of delivery in the first birth, with adjustment for confounders, (2) same parameter, with exclusion of women with persistent problems, and (3) examination of third births for women with a first birth vaginal delivery.
More complications and poorer infant outcome were found at later births when the first or second birth was by cesarean delivery than after a first spontaneous vaginal delivery, even when women with persistent problems were excluded. Women with instrument first births had a similar rate of complications in the second birth to women with spontaneous vaginal births, but some infant outcomes were poorer.
Problems that are subsequent to cesarean delivery are unlikely to be explained entirely by indications for cesarean delivery.

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    • "The enrolled population ranged from being all inclusive to being restricted to primiparous women who delivered a live singleton baby at term. Only four studies limited the cohort to low-risk pregnancies (Hemminki, 1987; Hemminki et al., 2005; Tollanes et al., 2007; Eijsink et al., 2008). Two studies reported separately the outcomes for women who had Caesarean section for breech presentation (Smith et al., 2006; Eijsink et al., 2008). "
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    ABSTRACT: Is there an association between Caesarean section and subsequent fertility? There is no or only a slight effect of Caesarean section on future fertility. Previous studies have reported that delivery by a Caesarean section is associated with fewer subsequent pregnancies and longer inter-pregnancy intervals. The interpretation of these findings is difficult because of significant weaknesses in study designs and analytical methods, notably the potential effect of the indication for Caesarean section on subsequent delivery. Retrospective cohort study of 1 047 644 first births to low-risk women using routinely collected, national administrative data of deliveries in English maternity units between 1 April 2000 and 31 March 2012. Primiparous women aged 15-40 years who had a singleton, term, live birth in the English National Health Service were included. Women with high-risk pregnancies involving placenta praevia, pre-eclampsia, eclampsia (gestational or pre-existing), hypertension or diabetes were excluded from the main analysis. Kaplan-Meier analyses and Cox proportional hazard models were used to assess the effect of mode of delivery on time to subsequent birth, adjusted for age, ethnicity, socio-economic deprivation and year of index delivery. Among low-risk primiparous women, 224 024 (21.4%) were delivered by Caesarean section. The Kaplan-Meier estimate of the subsequent birth rate at 10 years for the cohort was 74.7%. Compared with vaginal delivery, subsequent birth rates were marginally lower after elective Caesarean for breech (adjusted hazard ratio, HR 0.96, 95% CI 0.94-0.98). Larger effects were observed after elective Caesarean for other indications (adjusted HR 0.81, 95% CI 0.78-0.83), and emergency Caesarean (adjusted HR 0.91, 95% CI 0.90-0.93). The effect was smallest for elective Caesarean for breech, and this was not statistically significant in women younger than 30 years of age (adjusted HR 0.98, 95% CI 0.96-1.01). We used birth cohorts from maternity units with good quality parity information. The data are likely to be nationally representative because the characteristics of the deliveries in included and omitted units were similar. There may be residual bias in our adjusted results due to unmeasured maternal factors such as obesity and voluntary absence of conception. Any residual bias would lead to an overestimate of the effect of Caesarean section on fertility, and the true effect is therefore likely to be smaller than the effect reported in our study. Our results provide strong evidence that there is no or only a slight effect of Caesarean section on future fertility. The clinical and social circumstances leading to the Caesarean section have a greater effect on future fertility than the Caesarean section itself. This finding is important in light of rising Caesarean section rates. IG-U is supported by the Lindsay Stewart R&D Centre, Royal College of Obstetricians and Gynaecologists, UK. The authors have no conflicts of interest to declare. n/a.
    Preview · Article · Apr 2014 · Human Reproduction
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    • "The Caesarean delivery rate has increased markedly over the past two decades in countries throughout the world (Niino, 2011 ). Studies conducted in Africa, England, Finland, Norway, Scotland, Sweden and the USA have reported that women who deliver by Caesarean are less likely to have one or more subsequent live births than women who deliver vaginally (Zdeb et al., 1984; Hemminki, 1986; LaSala and Berkeley 1987; Hall et al., 1989; Hemminki and Merilainen 1996; Jolly et al., 1999; Hemminki et al., 2005; Mollison et al., 2005; Collin et al., 2006; Smith et al., 2006; Tollanes et al., 2007). However, the authors of a study of women undergoing planned Caesarean section for breech presentation in comparison with those with a spontaneous vertex vaginal delivery reported that the increased risk of not having a subsequent birth among those who had delivered by Caesarean section was no longer a strong association after adjustment for maternal and obstetric characteristics and concluded that 'It is unlikely that delivering by Caesarean section in a first pregnancy decreases a woman's likelihood of having a second viable pregnancy' (Smith et al., 2006). "
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    ABSTRACT: Is first birth Caesarean delivery associated with a lower likelihood of subsequent childbearing when compared with first birth vaginal delivery? In this study of US women whose first delivery was in 2000, those who had a Caesarean delivery were less likely to have a subsequent live birth than those who delivered vaginally. Some studies have reported lower birth rates subsequent to Caesarean delivery in comparison with vaginal delivery, while other studies have reported no difference. We conducted a retrospective cohort study of 52 498 women who had a first singleton live birth in the State of Pennsylvania, USA in 2000 and were followed to the end of 2008 via Pennsylvania birth certificate records to identify subsequent live births during the 8- to 9-year follow-up period. Birth certificate records of first singleton births were linked to the hospital discharge data for each mother and newborn, and linked to all birth certificate records for each mother's subsequent deliveries which occurred in 2000 to the end of 2008. Poisson regression models were used to evaluate the association between first birth factors and whether or not there was a subsequent live birth during the follow-up period. Over an average of 8.5 years of follow-up, 40.2% of women with a Caesarean first birth did not have a subsequent live birth, compared with 33.1% of women with a vaginal first birth (risk ratio (RR): 1.21, 95% confidence interval (CI): 1.18-1.25). Adjustment for the demographic confounders of maternal age, race, education, marital status and health insurance coverage attenuated the RR to 1.16 (95% CI: 1.13-1.19). Specific pregnancy and childbirth-related complications associated with not having a subsequent live birth included diabetes-related disorders, abnormalities of organs and soft tissues of the pelvis, fetal abnormalities, premature or prolonged rupture of membranes, hypertensive disorders, amnionitis, fetal distress and other maternal health problems. However, adjustment for the pregnancy and childbirth complications had little effect on the RR of not having a subsequent live birth (RR = 1.15, 95% CI: 1.11-1.19). We were unable to distinguish between women who did not have a subsequent live birth and those who moved out of the state, which may have introduced a selection bias if those who had Caesarean births were more likely to emigrate than those who delivered vaginally. In addition we were unable to measure pre-pregnancy body mass index, weight gain during pregnancy and prior infertility, which would have been helpful in our efforts to reduce selection bias. The results of this study provide further corroboration of previous studies that have reported reduced fertility subsequent to Caesarean section in comparison with vaginal delivery. This study was funded by the US National Institute of Child Health and Human Development (NICHD, R01-HD052990). No competing interests are declared.
    Preview · Article · Sep 2013 · Human Reproduction
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    • "These datasets provide a rich description of patient characteristics, which can support more adequate selection of comparative populations and better risk adjustment. For example, they restricted enrolled populations to low-risk singleton primiparous deliveries (Smith et al., 2006; Tollanes et al., 2007) or adjusted for confounding factors such as maternal age (Hemminki et al., 2005; Smith et al., 2006). "
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    ABSTRACT: STUDY QUESTION: Is there an association between a Caesarean section and subsequent fertility? SUMMARY ANSWER: Most studies report that fertility is reduced after Caesarean section compared with vaginal delivery. However, studies with a more robust design show smaller effects and it is uncertain whether the association is causal. WHAT IS KNOWN ALREADY: A previous systematic review published in 1996 summarizing six studies including 85 728 women suggested that Caesarean section reduces subsequent fertility. The included studies suffer from severe methodological limitations. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis of cohort studies comparing subsequent reproductive outcomes of women who had a Caesarean section with those who delivered vaginally. PARTICIPANTS/MATERIALS, SETTING, METHODS: Searches of Cochrane Library, Medline, Embase, CINAHL Plus and Maternity and Infant Care databases were conducted in December 2011 to identify randomized and non-randomized studies that compared the subsequent fertility outcomes after a Caesarean section and after a vaginal delivery. Eighteen cohort studies including 591 850 women matched the inclusion criteria. Risk of bias was assessed by the Newcastle-Ottawa scale (NOS). Data extraction was done independently by two reviewers. The meta-analysis was based on a random-effects model. Subgroup analyses were performed to assess whether the estimated effect was influenced by parity, risk adjustment, maternal choice, cohort period, and study quality and size. MAIN RESULTS AND THE ROLE OF CHANCE: The impact of Caesarean section on subsequent pregnancies could be analysed in 10 studies and on subsequent births in 16 studies. A meta-analysis suggests that patients who had undergone a Caesarean section had a 9% lower subsequent pregnancy rate [risk ratio (RR) 0.91, 95% confidence interval (CI) (0.87, 0.95)] and 11% lower birth rate [RR 0.89, 95% CI (0.87, 0.92)], compared with patients who had delivered vaginally. Studies that controlled for maternal age or specifically analysed primary elective Caesarean section for breech delivery, and those that were least prone to bias according to the NOS reported smaller effects. LIMITATIONS, REASONS FOR CAUTION: There is significant variation in the design and methods of included studies. Residual bias in the adjusted results is likely as no study was able to control for a number of important maternal characteristics, such as a history of infertility or maternal obesity. WIDER IMPLICATIONS OF THE FINDINGS: Further research is needed to reduce the impact of selection bias by indication through creating more comparable patient groups and applying risk adjustment. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: n/a.
    Preview · Article · May 2013 · Human Reproduction
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